Recently, the development of new renewable energy has become more important and interested due to the serious environmental pollution and the lack of fossil fuel. Among the new renewable energy, a solar cell is spotlighted as a pollution-free energy source for solving the future energy problem because it rarely causes environmental pollution and has the semi-permanent life span and there exists infinite resources for the solar cell.
A solar cell may be defined as a device to convert light energy into electrical energy by using a photovoltaic effect of generating electrons when light is incident onto a P-N junction diode. In addition, a modularized solar cell is called a PV module (photovoltaic module).
As described above, since the solar cell uses solar energy, it is required to obtain solar energy from the sun as much as possible to improve the efficiency of the solar cell.
When taking into consideration the revolution of the sun for a day, that is, the diurnal motion of the sun, as generally known, the sun rises in the east and sets in the west. In other words, an angle of sun light absorbed by the solar cell is varied over time.
Meanwhile, a solar cell according to the related art has a problem in that the solar cell remains at a constant angle. That is, the duration of sunshine is about 3 hours to 4 hours in summer and about 2 hours to 3 hours in other seasons. Thus, to improve the efficiency, it is necessary to increase the incident angle of sunlight upon the solar cell at a maximum level as long as possible in the duration of sunshine.
To solve the above problems, an incident plane of a solar cell module or incident planes of solar cell modules fixed to one member may be controlled according to the incident angle of sunlight. However, in this case, since each solar cell module must be rotated, the efficiency may be deteriorated.